Electronic Attack (EA) and Electronic Support Measures (ESM) systems require large bandwidth capabilities. In other words, such systems should be capable of processing a broad range of frequency components from an input signal. Heterodyne architectures are not well adapted to this requirement, limiting the instantaneous bandwidth. Sampling systems, by contrast, overcome this limitation and have shown good performance for low to medium frequencies. However, frequency conversion of high frequencies by sampling still remains challenging. The upper frequency limit of sampling systems depends on the signal fidelity required. For ESM systems this is typically about 10 to 20 GHz.
In particular, problems may arise due to incompatibilities between the band pass characteristics of a typical system of interest and those of the system that is used to actually sample the incoming or outgoing signal. In current systems, in order to process the incoming/outgoing signal with high fidelity, it is necessary to split the spectrum, by the use of analogue filters, into different frequency bands, which are processed separately. Each of these bands has lower and upper frequency limits.
Conventional sampling systems are inherently low-pass systems, having an input bandwidth that extends from 0 to an upper limit. Increasing the upper limit of the sampler reduces the signal fidelity and therefore samplers only achieve limited signal fidelity in the high frequency bands.
Thus, there is a need to provide a band pass sampling device having an improved performance for a given input bandwidth.